Field of the Invention
The present invention relates to a lamination molding device.
Background of the Invention
In a powder sintering/laminating method (laser lithography) of metal using laser beam, a particular smoke known as fume is generated when the metal material powder is irradiated with laser beam for sintering. When the chamber gets filled with fume, the fume may shield the laser beam, and the laser beam with necessary energy may not reach the sintering portion.
Current laser lithography apparatus (sintering lamination molding apparatus) for molding metal products is generally operated by supplying the material powder in a chamber filled with inert gas (usually nitrogen gas), followed by irradiation of the material powder with the laser beam.
In order to stably emit the laser beam, it is necessary to maintain the concentration of the inert gas in the chamber at a constant level. Accordingly, constitution is made so as to allow discharge of the contaminated inert gas in the chamber while supplying the clean inert gas. Management of the inert gas in the chamber is basically conducted by the supply/discharge opening arranged at upper left and right sides of the chamber.
Removal of the fume by supplying and discharging the inert gas for maintaining the environment in the chamber enables to remove the obstacle during irradiation with the laser beam. However, such removal is still insufficient. In particular, when the laser beam is emitted from the upper side of the chamber, even a scarce amount of fume continuously rising towards the lens would contaminate the lens, and may result in termination of the molding process.
In Patent Literature 1, a gas of a different type or a gas having a different temperature with respect to the inert gas in the chamber is supplied from the upper side of the chamber in order to remove the fume from the optical pathway of the laser beam.